So eventually I got one in from Sweden via the local Volvo dealership and (because they were chokka in their workshop) got my local tyres and exhaust place to fit it.
So sorted - albeit at a cost of about £390
The nearest exhaust fabricator would only give me a ballpark price of between £350 and £450 plus fitting. Plus it would have meant a day of my time to go and wait while they did it.